In order to use mobile communication network resources effectively, WCDMA/GSM global standardizing organization 3GPP proposed the broadcast/multicast service (BCMCS), with which a Point To Multi-Point service of sending data from one data source to multiple users may be provided in a mobile communication network, thereby realizing network resources sharing and improving the utilization rate of the network resources, especially the air interface resources. The broadcast/multicast service defined by 3GPP may realize not only a low speed message type broadcast/multicast which contains plain text, but also a broadcast/multicast of a high speed multimedia service, which is in accordance with the tendency of future mobile data service development.
The multicast/broadcast service is based on a WCDMA/GSM packet network. By adding some new function entities such as a broadcast/multicast service controller, the BCMCS function is added to the existing packet domain function entities such as packet data service nodes (PDSN), radio network controllers (RNC) and user equipments (UE), etc. and new logically shared channel is defined so as to realize air interface resources sharing.
The major technical feature of the broadcast/multicast service (BCMCS) is that the air interface traffic channel is a shared broadcast channel which may provide information of the same contents to a plurality of users simultaneously. If the BCMCS is implemented in a wireless communication system, the BCMCS such as TV-On-Mobile may be operated in wide range with low cost, thus giving prominence to the advantage in operation of the 3G network. BCMCS is a major service in a 3G network.
The architecture of a BCMCS network will now be described. As shown in FIG. 1, a BCMCS network specifically includes:
A BCMCS controller: i.e. the IP host in the operator network used for storing session information of BCMCS, the session information includes: correspondence relationship between a program title and a multicast address, a port number and the ID of a BCMCS stream; the information of the service bearer, such as the IP header compression parameter; and parameters relating to encryption and security, such as broadcast access key (BAK). The BCMCS controller is used for providing BCMCS session information to a terminal in the process when the terminal initiates a “content information acquisition” to inquire the session information, and for providing session information to a broadcast serving node (BSN), an access network/packet control function (AN/PCF) unit, and a content server, so as to establish the service bearer. Meanwhile, the BCMCS controller also participates in user authentication.
A BCMCS content server: which is used for converting contents from a service provider into a format required by the session, for example, a designated encoding format, according to the session information stored in the BCMCS controller, and for converting BCMCS contents into an IP multicast stream and forwarding the stream to a multicast router (MR).
A BCMCS content provider: which is a provider of BCMCS contents, the contents may be provided by a third party content provider or by the operator itself.
A BCMCS Service Node (BSN): the A10 service bearer established by the BSN is unidirectional, and only performs point-to-point protocol (PPP) encapsulation. The mode of header compression of the BSN is not negotiation but obtaining from the BCMCS controller. The BSN interfaces upwardly only with the BCMCS controller and the content server, and negotiates with the multicast router to join the multicast group, so as to obtain the IP multicast stream of MCMCS.
A Multicast Router (MR): which is a standard multicast router complying with IETF RFC. If the multicast IP stream between the content server and BSN is transmitted through a tunnel, this network element may be omitted.
An Access Network/Packet Control Function (AN/PCF) unit: which is responsible for establishing and releasing the bearer between an AT (terminal) and the BSN. This unit may also perform link layer encryption for the borne services.
An Authentication/Authorization/Accounting server (AAA): which is responsible for performing authentication, authorization and accounting for the BCMCS, and providing information about the services subscribed for by a user to the BCMCS controller.
A Packet Data Service Node (PDSN): which may communicate with the AN/PCF to establish and release the bearer of a unicast IP stream in the wireless network, and may establish a PPP connection with the AT, so that the AT may obtain the unicast IP address and establish communication with the BCMCS controller.
Now the process of broadcast/multicast will be described with reference to the drawings.
Firstly, the operator issues to the AN/PCF and BCMCS controller information about bandwidth of each stream and the strategies such as whether a soft combination is needed. The BCMCS controller, the AAA server, the CS (Content Server) and the BSN are configured according to the strategies of the operator.
After configuring the corresponding information, the subscriber obtains the program title from the website run by the operator. The subscriber (MS) firstly finds the BCMCS controller address through the configured BCMCS controller address or through a Dynamic Host Configuration Protocol (DHCP); then obtains program information, time information, etc. from the BCMCS controller by means of the Wireless Application Protocol (WAP), Hyper Text Transmission Protocol (HTTP), Short Message Service (SMS) or terminal built-in BCMCS applications etc.
The subsequent process is as shown in FIG. 2, which includes:
step 11: the MS sends a message to the BCMCS controller to obtain session related information of the BCMCS program: BCMCS_FLOW_ID, compression parameters, multicast address/port, security-related parameters, such as BAK. The message carries identification information of the MS;
step 12: the BCMCS controller returns an authentication challenge to the MS after receiving the message from the MS requesting to obtain the program title;
step 13: the MS calculates a response value based on the authentication challenge and a Register Key (RK), and sends the response value to the BCMCS controller through a request message;
the RK was obtained when the subscriber activated the service, and the RK and the relevant accounting category information was also obtained by the AAA server;
step 14: the BCMCS controller sends a request message to the AAA server, wherein the authentication response information returned from the MS is carried in the message;
step 15: after receiving the request message, the AAA server performs access authentication on the MS by means of the RK in the message;
step 16: the AAA server sends the program allowed to be watched by the MS, a temporary key (TK) generated with the RK of the subscriber and a TK_Rand to the BCMCS controller according to the result of the authentication;
step 17: the BCMCS controller performs an encryption on the program that may be watched and the corresponding BAK with the TK, and then distributes the relevant information of the program and the TK-Rand to the MS at the same time. Upon reception, the terminal MS generates the TK by using the RK stored in the terminal itself and the acquired TK-Rand, so as to decrypt the BAK, then the corresponding program may be watched with the BAK.
After the above processes, the subscriber MS starts to monitor system messages of the present cell to receive the BCMCS program broadcasted in the cell.
The specific registration process is as shown in FIG. 3, which includes the following steps:
step 21: the MS sends a registration message to the AN/PCF or BSC/PCF, the registration message carries the authentication signature and stream identification information;
step 22: the AN/PCF sends a broadcast service request message to BSN;
step 23: the BSN forwards the broadcast service request message, i.e. the request message, to the BCMCS controller;
the format of the request message is as shown in table 1:
TABLE 1Information ElementElement DirectionA9 Message TypeBS/AN→PCFCorrelation IDBS/AN→PCFMobile Identification (IMSI/ATI)BS/AN→PCFBCMCS Flow and Registration InformationBS/AN→PCF
step 24: the BCMCS controller authenticates the registration of the MS after
receiving the message, and requests to establish a service bearer;
meanwhile, the BCMCS controller configures the mapping relationship between the physical channel and the logical channel as well as the correspondence between the logical channel and the stream ID according to the bandwidth requirement of the stream provided by the operator and the network coverage condition;
step 25: the BSN establishes the corresponding service bearer and returns an allowing access message to the AN/PCF;
the allowing access message carries common session information, BSN session information, and RN session information;
step 26: the BSC/PCF sends a registration request message to the BSN;
step 27: the BSN returns a registration response message to the BSC/PCF, so as to complete the process of registration to the BSN;
step 28: a service bearer is established between the MS and the content server, then the BCMCS (i.e. program stream information) on the content server may be sent to the corresponding MS via the service bearer.
The BSN is also used for collecting accounting information to report to the AAA server, so that the AAA server may perform user accounting.
It may be seen from the above prior art that, at present, the BCMCS request message involves only authentication with respect to the user, but no authentication with respect to the area. However, in the practical development of services, an operator may hope that certain programs are broadcasted only in specific areas. Moreover, at present, subscribers or AN/PCF are not divided according to the area with respect to the broadcasted services. Meanwhile, the accounting approach for the same stream in the prior art is not able to support the difference among areas.
The service establishment initiated from the network side does not include the area information at present, which may cause a BCMCS program to be established over a large area and results in waste of resources. Therefore, a pertinent area management mechanism is lacking.